Methods and devices for hydraulic fracturing design and optimization: a modification to zipper frac

Abstract

The present invention provides a method of optimizing the placement of fractures along deviated wellbores by hydraulically fracturing a well to form a complex fracture network of hydraulically connected fractures.

What is claimed is: 
     
       1. A method of hydraulically fracturing a subterranean formation to form a complex modified zipper fracture pattern of hydraulically spaced fractures between adjacent wellbores comprising steps of:
 identifying at least a first wellbore and a second wellbore that are laterally parallel in a subterranean formation; 
 forming a modified zipper fracture pattern between the first wellbore and the second wellbore, wherein the modified zipper fracture pattern is formed by:
 (a) introducing a first fracture, a second fracture, and a third fracture in the first wellbore; 
 (b) introducing in the second wellbore a fourth fracture that extends to a first intermediate area between the first fracture and the second fracture to alter the stress field in the first intermediate zone; and 
 (c) introducing in the second wellbore a fifth fracture that extends to a second intermediate area between the second fracture and the third fracture to alter the stress field in the second intermediate zone; and 
 
 forming one or more complex modified zipper fracture pattern by repeating steps (a), (b) and (c) to extend the modified zipper fracture pattern. 
 
     
     
       2. The method of  claim 1 , further comprising the step of introducing a third parallel lateral wellbore in the subterranean formation parallel to the second wellbore and introducing a third wellbore fracture in the third parallel lateral wellbore between the fourth fracture and the fifth second fracture that extends to the first a third intermediate zone between the fourth fracture and the fifth second fracture to alter the stress field in the third intermediate area. 
     
     
       3. The method of  claim 1 , wherein the complex modified zipper fracture pattern connects to one or more pre-existing networks of natural fractures. 
     
     
       4. The method of  claim 1 , wherein the fourth fracture and the fifth fracture reduce a stress anisotropy between a first and second horizontal stress. 
     
     
       5. The method of  claim 1 , wherein the fourth fracture and the fifth fracture change the magnitude of horizontal stresses. 
     
     
       6. The method of  claim 1 , wherein the fractures form in more than one direction. 
     
     
       7. The method of  claim 1 , wherein the subterranean formation comprises a shale or a tight sand reservoir. 
     
     
       8. The method of  claim 1 , wherein the first wellbore, the second wellbore or both are deviated wellbores. 
     
     
       9. A method of altering the stress anisotropy in a subterranean formation by hydraulically fracturing in a specific modified zipper sequence comprising the steps of:
 identifying at least two parallel lateral wellbores in a subterranean formation comprising at least a first wellbore and a second wellbore; 
 forming a modified zipper fraction pattern comprising one or more modified zipper fraction pattern segments each comprising: 
 introducing at least forming a first fracture in the first wellbore to generate a first stress field; 
 forming a second fracture in the first wellbore to generate a second stress field; 
 forming a third fracture in the second wellbore that extends between the first fracture and the second fracture to generate a third stress field, wherein the third stress field extends to an intermediate area between the first stress field and the second stress field to alter a regional stress field so that the difference between the first stress field and the second stress field approaches zero; and 
 forming one or more complex fractures extending from the first fracture, the second fracture, the third fracture or a combination thereof to form a complex fracture network. 
 
     
     
       10. The method of  claim 9 , further comprising the step of extending the modified zipper fraction pattern by adding one or more modified zipper fraction pattern segments. 
     
     
       11. The method of  claim 9 , wherein the one or more complex fractures connects to one or more pre-existing networks of natural fractures to form the complex fracture network. 
     
     
       12. The method of  claim 9 , wherein the one or more complex fractures form in more than one direction. 
     
     
       13. The method of  claim 9 , wherein the subterranean formation comprises a shale or a tight sand reservoir. 
     
     
       14. The method of  claim 9 , wherein the two or more parallel lateral wellbores are deviated wellbores. 
     
     
       15. A method of optimizing the placement of fractures along deviated wellbores comprising steps of:
 identifying at least two parallel lateral wellbores in a subterranean formation comprising at least a first wellbore and a second wellbore; 
 forming a modified zipper fraction pattern between the first wellbore and the second wellbore by 
 forming a first series of fractures in the first wellbore that extend toward the second wellbore into an intermediate area; and 
 forming a second series of fractures in the second wellbore that extend into the intermediate area between the first series of fractures to alter a stress field in the intermediate area to optimize the placement of fractures. 
 
     
     
       16. The method of  claim 15 , further comprising the step of introducing a third parallel lateral wellbore in the subterranean formation parallel and adjacent to the second wellbore; forming a third series of fractures in the third wellbore that extend into a third intermediate area between the second series of fractures to alter the stress field. 
     
     
       17. The method of  claim 16 , further comprising the step of introducing a fourth parallel lateral wellbore in the subterranean formation parallel and adjacent to the first wellbore, the second wellbore or the third wellbore, forming a fourth series of fractures in the fourth wellbore that extend into a fourth intermediate area between the first series of fractures, the second series of fractures or the third series of fractures to alter the stress field. 
     
     
       18. The method of  claim 15 , further comprising the step of extending the modified zipper fraction pattern between the first wellbore and the second wellbore by adding one or more modified zipper fraction patterns.